Considering the fact that on Discovery the Land Rover button on the fob can be programmed to turn on the low beam and also it's generally not used so much, I've made a little logic in order to use these things for starting the FBH.
Normally, the low beam is ON only when the ignition is ON. Well, the only time it will be ON when the ignition is OFF is when you press that button on the remote.
With a small microcontroller, in which I've implemented a part of the W-Bus serial protocol, I solved the problem.

Now, when you need the FBH, turn ON the low beam with the remote control for 2-3 seconds and that microcontroller sees that the lights were ON and then turned OFF after a short period of time when the ignition was OFF and turns the heater ON for 15 minutes.
I've put a limit of 15 minutes for battery health and anyway it's enough to bring the coolant temperature to 70-80 degrees.

In fact the logic is this:
- if the lights are turned on between 1 to 5 seconds, the FBH starts.
- if the lights are turned on between 5 to 15 seconds, the FBH stops.
- normal button/low beam usage of 30 seconds or more doesn't affect the FBH.

Below schematic diagram and hex file to be programmed into the microcontroller using any PIC programmer. (found on the net, some even home-made). The signals are self-explanatory.
Also the source code is available for those that want to improve it, but for many the PIC's firmware could be enough in order to get things done.

As a different approach, the LOW BEAM signal can be driven by any remote control (radio, GSM, etc) that can pulse that input for 2-3 seconds.
But the Land Rover button approach can be enough for the one that have the car on the driveway and sees its lights. The range of the fob is quite enough.

A few later words...
It is known that if you're using a 1533 timer, when you wake up the car, the FBH will stop.
Because this implementation is using, in its dialog with the FBH, the same addressing mode as the Webasto Thermo Test program, the FBH will keep running even if you're waking up the car with the remote or any other means.

UPDATE, November 16, 2014 - Version 1.06http://www.disco3.co.uk/gallery/albums/use...r_v106.rar
This version has both a time limit (15 minutes) and a temperature target (75 degrees Celsius)
If you want to modify them, you can adjust them inside the source code (MINS_TO_RUN, MAX_TEMP) and then the sources must be recompiled.
This way things are optimized, meaning whichever condition is reached first will stop the FBH.
Any combination of conditions can be made.
For time limit only, set a target temperature to an unrealistic temperature, for example 150 degrees.
For temperature limit only, set a time limit to an unrealistic time, for example 250 minutes.

Â There are only 2 things to make the universe work properly - Duct tape and WD40.
If it moves and it shouldn't - Duct tape. If it doesn't move and it should - WD40.
Everything else is just stuff.

Last edited by alex_pescaru on 17th Nov 2014 8:23 am. Edited 11 times in total

So basically you can turn on the FBH using the landrover button on the Key?? That would be a great achievement Defender 90 CSW MY06
Discovery 3 SE MY05 (Gone but still on the forum )
Defender 90 CSW MY02 ( Gone)
Discovery 3 GS MY08 ( Gone)

As for sale....
All it's a hobby and for me this means: concept, design, test, share, move on... So, no sale...
But if anyone wants to do it, or to improve it, just go for it. As I've said, I will share the sources if needed.

It works on my Freely2. A couple of my friends also built it for their cars and I know of a Disco3 owner that had built it (with a small modification, another line driver).

W-Bus protocol: spy on a communication between a TTV and a 1533 timer and the internet
( http://sourceforge.net/projects/libwbus/ )There are only 2 things to make the universe work properly - Duct tape and WD40.
If it moves and it shouldn't - Duct tape. If it doesn't move and it should - WD40.
Everything else is just stuff.